Nonlinear Vibration Characteristic Analysis Of High-voltage Transformation Line System

High voltage transmission line, as a kind of large-span structure form of high softness, it has nonlinear characteristics. In the current specifications for the design of the tower line system, the transmission towers and power lines is separately designed. The transmission lines are subject to the wind load as static load applied to the thread point, design procedures for considering the effects of wind-induced vibration transmission line is only general using a wind load adjustment factor to calculate. Thus, from an overall perspective line system to analyze the mutual influence of vibration transmission tower and power lines, for a more accurate grasp of the nature of the nonlinear vibration characteristics and system response characteristic line system under wind loads have greater practical significance, but also to provide a reference for the rational design of the tower line system.This paper describes the finite element modeling of the process line systems, the expression of wind loads and the wind field simulation. Then the transmission lines were obtained modal analysis and calculate the transmission line damping matrix. Free vibration response of high-voltage transmission line system, the harmonic excitation vibration response and the design wind speed of response has been analyzed, and change the damping, free vibration initial potential energy, excitation amplitude and other conditions.Through computational analysis, the main conclusions of this article are as follows:(1)The high-order vibration frequency and the base power lines of inside and outside surfaces is with an approximate frequency of vibration of an integer multiple of the relationship between the inner and outer surfaces with a high-order vibration frequency is approximately 1: 1 relationship, the nature of the nonlinear transmission line has. The high-order vibration frequency and the base frequency of vibration of the inner and outer surface has an relation of approximate integral multiple. The high-order vibration frequency of inner and outer surfaces is with a approximately 1: 1 relationship, so the power line is nonlinear constitutionally.(2)Under the free vibration condition, inner and outer surface vibration transmission lines would coupling occurs, a great amplitude of displacement and dynamic tension will happen, vibration energy transfer between the inner and outer surfaces. With the initial energy increases, the coupling phenomenon will become more obvious, damping can not inhibit the generation of resonance. Energy transmission lines will be transferred to the excited indirect transmission tower, the response characteristics of the transmission tower showing divergence. Under the conditions of the larger initial energy, without considering the tower line coupling effect is somewhat dangerous.(3)Under the harmonic excitation, power lines will have primary resonance, the magnitude of the displacement and dynamic tension will significantly increase. With increasing excitation amplitude, resonance phenomenon is more pronounced. Transmission towers and power lines also produce more intense than the free vibration resonance response. Due to the lack of constraints insulators, ground wire is more sensitive than the harmonic excitation, the tower will lead to a more intense response. Harmonic excitation, transmission tower to consider coupling effects, super harmonic excitation in accordance with the standard design is safe.(4)For the linear vibration, damping settings have a good amplitude suppression effect, but for nonlinear vibration damping system settings may lead to divergent vibrations, then make structure reflects the unstable vibration characteristics. Line system in harmonic excitation and wind-induced vibration, damping vibration system settings will not necessarily play an inhibitory effect. So in the project, damping device should be rationally designed to be placed.(5)Wind loads on transmission lines, due to the role of internal resonance, vibration energy will be shift from transmission line to transmission tower. At this point, the vibrational energy tower contains resonance energy transfer within the transmission line and the energy due to wind loads. Therefore, the coupling transmission line system can not be ignored.